SAN FRANCISCO — Yahoo is planning to lay off hundreds of employees in an effort to increase its profitability, prop up its deflated stock price and narrow the focus of its sprawling Internet portal to a smaller number of crucial areas, people close to the company said Monday.

The final number of layoffs from Yahoo’s work force of about 14,000 is yet to be determined and is likely to be announced around the end of the month, perhaps during Yahoo’s conference call on Jan. 29 with analysts after it reports fourth-quarter results, these people said.